In consequence of the attack on Pearl Harbor, the United States Air Force determined that large training bases should be located far inland so that they would not be vulnerable to coastal attack. Almost equidistant from the three major western ports of Seattle, San Francisco, and Los Angeles and about halfway between Canada and Mexico, northern Utah sat in an ideal location, situated as to be readily defensible and easily accessible by railroad, automobile, and airplane. Colonel E.G. Thomas combed the area in early 1942 searching for good drainage, an accessible water supply, and a climate friendly to aircraft landings for an air corps training base.

Colonel Thomas recommended a 5,450-acre dry farming area in Kearns, about fourteen miles west of Salt Lake City. The Army proceeded rapidly with construction, intending the base to be a temporary unit. From April 7 to May 22, 1942, the base grew with the installation of water mains, sewage systems, streets, tarpaper buildings, and electrical systems capable of supporting 30,000 to 70,000 people. They also built a railroad spur from the Denver and Rio Grande as well as a fence around the base. By August 21,1942, all the barracks had been completed at an estimated total cost of $17 million. Upon completion, the post boasted 1.7 million square feet of warehouse space, 926 tarpaper buildings, theaters, gymnasiums, fire stations, recreation fields, chapels, barbershops, a ten-wing hospital, a railroad station, a post office, a library, a cold storage plant, and a bank. Furthermore, 25,000 trees, shrubs, and grass were planted to keep the dirt in place while beautifying the base.

Throughout World War II the Kearns Air Base served primarily as a training field for Air Corps personnel. The base officially opened as an adjunct of the Army Air Force Training Command on July 20, 1942, and on August 15 became a basic training center. The training facilities included a grenade-throwing ground, a gas demonstration area, beachhead maneuvers, and a mile-long obstacle course. Additionally, Kearns Air Base had Utah's second largest hospital, one of two sewage treatment plants in the state, one of the largest dental installations in the country, and the nation's second largest rifle range. By the spring of 1943, Kearns had grown into Utah's third largest city and at its peak, stationed 40,000 troops and employed nearly 1,200 civilians.

Residents of Salt Lake City were not hospitable to the servicemen, but resisted complaining about the base due to its beneficial effect on Utah's economy. With the end of World War II, the War Assets Administration declared Kearns Air Base surplus and planned to return it to farmland. This plan met with blatant opposition by Utahns who argued that the "Army had laid out a model city." So the War Assets Administration opened the base to public bidding and in July 1948, Standard Surplus Incorporated of New York bought this ready-made housing development, complete with utilities, streets, and two million feet of board lumber.

In the boom following World War II, the newly established city of Kearns became one of Utah's fastest growing communities. It experienced a steady population increase throughout the last half of the 20th century. Kearns is currently an unincorporated area in Salt Lake County and is the sixth largest city in Utah with an estimated population of 44,500.